SAM
Also written as: SAM — Systolic Anterior Motion
Abnormal anterior movement of the mitral valve during systole, potentially causing LVOT obstruction.
Full Definition
SAM (Systolic Anterior Motion) refers to the abnormal anterior displacement of the mitral valve apparatus toward the interventricular septum during systole, which can result in left ventricular outflow tract obstruction. SAM most commonly occurs in hypertrophic cardiomyopathy but can also be seen with mitral valve prolapse, after mitral valve repair, or in hyperdynamic states. The mechanism involves Venturi effect and drag forces that pull the mitral leaflets anteriorly during systolic ejection. SAM can be classified as mild (leaflet tip contact), moderate (mid-leaflet contact), or severe (extensive leaflet-septal contact). Dynamic LVOT gradients and mitral regurgitation often accompany significant SAM.
Usage
Usage note: Always capitalize SAM when abbreviated; grade severity based on leaflet-septal contact extent.
In Context
- "Severe SAM with mitral-septal contact was observed, creating a peak LVOT gradient of 80 mmHg." — Hypertrophic cardiomyopathy report
- "Post-repair echocardiography revealed mild SAM without significant LVOT obstruction." — Post-surgical evaluation